JPS6224785Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE The present invention relates to an intake air heating device primarily used in diesel engines.

In order to maintain good ignitability when starting an engine, it is already well known that an air heater is interposed in a part of the intake passage to heat intake air at the time of starting the engine.

This air heater generates heat when electricity is supplied from the battery, but since diesel engines generally have a high compression ratio, a large driving force is required from the starter motor during starting cranking, and a large current is required to drive the starter motor. When the air heater was energized, the starting rotation decreased, making it impossible to start the engine smoothly.

In view of this, the present applicant has proposed a device in Japanese Utility Model Application Laid-open No. 156238/1983, which cuts off the power supply to the air heater during cranking of the engine.

However, when the air heater is completely de-energized at the time of starting, the effect of heating the intake air is halved, and there is a problem in that starting performance, especially during low-temperature starting, is reduced.

In order to solve this problem, the present invention installs two air heaters in the intake passage, or an air heater with a circuit divided into two systems, and energizes only one heater during cranking to start cranking. An object of the present invention is to provide an intake air heating device for an internal combustion engine, which maintains intake air heating without reducing the engine speed and improves startability.

Hereinafter, embodiments of the present invention will be described based on the drawings.

In the embodiment shown in FIG. 1, 1 is a battery, and 2 is a battery switch, which turns battery switch 2 ON.
, the normally open contact 3A of the battery relay 3 closes. 4 is an engine key switch having a starter contact 4A and two heater contacts 4B and 4C.

When the starter contact 4A is turned on, the starter relay 5 is energized, and the starter motor 6 is energized through its normally open contact 5A to perform starting cranking, and the normally closed contact 7 of the start detection relay 7 is energized.
B opens.

On the other hand, either heater contact 4B or 4C is ON.
, the first heater relay 9 is energized via the air heater timer 8, closes its normally open contact 9A, and energizes one of the air heaters 10.
The second heater relay 11 is energized via the normally closed contact 7A of the start detection relay 7, and its normally open contact 11
The other air heater 12 is energized through A.

Air heaters 10 and 12 are installed in series in the engine intake passage, and when both heaters 10 and 12 are generating heat, predetermined intake air heating is performed, but even if only one of them generates heat, the intake air The capacity is set so that adequate intake air heating can be performed when the flow rate is low.

The system is constructed as described above, and its operation will be explained next.

When the battery switch 2 is turned on and the engine key switch 4 is turned to the starter side, the starter contact 4A and the heater contact 4B are turned on.

Then, the starter relay 5 is energized, the starter motor 6 is energized, and the engine is cranked.

At the same time, the first heater relay 9 is excited via the air heater timer 8, and the air heater 10 is energized.

At this time, the start detection relay 7 is connected to the starter contact 4.
Since the normally closed contact 7B is opened, the second heater relay 11 is de-energized and the air heater 12 is not energized.

Therefore, during starting cranking, the capacity of the air heater is halved, and since sufficient drive current is supplied from the battery 1 to the starter motor 6, the starter rotation increases to a predetermined value, and the capacity of the air heater is halved. However, the intake air flow rate at startup is less than half of that after self-sustaining operation.
It is possible to heat the intake air to a predetermined level, and these factors combine to ensure good starting performance.

After starting, when switching to self-sustaining operation and turning on the key switch 4 to the heater contact 4C, the starter contact 4A
is turned off, power supply to the starter motor 6 is stopped, and the start detection relay 7 is de-energized and its contact 7B is closed.

Therefore, with the current from air heater timer 8,
The second heater relay 11 is energized via the contact 7B, and in order to close the normally open contact 11A, the second air heater 12 is also energized and starts generating heat.

In this way, when the amount of intake air increases due to the transition to self-sustaining operation (warm-up operation), the two air heaters 10 and 12 are energized in response to this, increasing their calorific value and heating the intake air to a predetermined level. This will promote warm-up.

Note that when the time set by the air heater timer 8 passes, that is, the time is up, the first and second
The power supply to heater relays 9 and 11 is cut off, and both of their contacts 9A and 11A are turned off, so that air heaters 10 and 12 stop generating heat.

In the embodiment shown in FIG. 2, the energizing circuits for air heaters 10 and 12 are divided, and one heater relay
or 11, energization of some heater wires of each of the air heaters 10 and 12 is controlled.

Therefore, when the second heater relay 11 is OFF, the first and second air heaters 1
0 and 12 each generate half the heat.

As described above, according to the present invention, when cranking to start the engine, the capacity of the air heater is reduced to ensure the drive current for the starter motor, so it is possible to prevent the cranking rotation from decreasing even when starting at a low temperature. In addition, since the small flow rate of intake air during cranking can be sufficiently heated even by a small capacity air heater, the engine starting characteristics can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a first embodiment of the present invention, and FIG. 2 is a circuit diagram of a second embodiment. 1...Battery, 4...Key switch, 6...
Starter motor, 7...Start detection relay, 8...
Air heater timer, 9, 11...Heater relay,
10, 12...Air heater.

Claims (1)

[Scope of utility model registration request] While installing two air heaters in the intake passage or an air heater with a current-carrying circuit divided into two systems,
Intake air heating for an internal combustion engine, characterized in that a start detection relay contact interlocked with a starter relay is provided, and control means is provided for energizing only one or a part of the air heaters when the starter is activated through the start detection relay contact. Device.